Research On Synthesis And Performance Of Active Group Cationic Gemini Surfactants

Gemini surfactant possesses higher surface activety, lower critical micelle concentration, more unique rheological property, better resistance to salt, more effective wetting properties, better water solubility, et al than those of traditional surfactant because of its special molecular structure, which makes it promising in the mining, chemical engineering, nanotechnology, daily chemistry and other fields. However, due to its simple action of hydrophobic alkyl carbon chain in the molecular, hardness to degrade, and many of other shortcomings, Gemini surfactant can hardly meet people’s needs. The requirement to develop multi-purpose Gemini surfactant has come to put forward. In order to improve the performance of the Gemini surfactant, a series of cationic ester-type Gemini surfactants containing polymerizable carbon-carbon double bond have been synthesized.Firstly, a kind of intermediate called methyl acryloyl ethyl epoxy propyl dimethyl ammonium chloride (ODEAC) was synthesized with dimethyl amino ethyl methacrylate (DM) and epoxy chloropropane (ECH) as the main raw materials through nucleophilic reaction to replace quaternary ammonium. Single factor experiment was used to discuss the reaction solvent, reaction temperature, material ratio and reaction time on conversion rate and epoxy value of the product to determine the optimal synthetic process. Secondly, a series of non-symmetrical active groups contained cationic Gemini surfactants C12-3(OH)-DM, C14-3(OH)-DM, C16-3(OH)-DM and C,8-3(OH)-DM were synthesized through three-step reaction using reactive intermediates oxygen ethyl dimethyl methyl acryloyl epoxy propyl chloride (ODEAC), four kinds of long chain alkyl tertiary amine (12DMA、 14 DMA、16 DMA �'� 18 DMA) and hydrochloric acid as the main raw material.Infrared spectrometer, nuclear magnetic resonance instrument, elemental analyzer, surface interface tensionmeter, ultraviolet spectrum, foam performance, emulsifying properties and some other analysis methods were introduced and studied to characterize the molecular structure and physical and chemical properties of aqueous solution of the products. The results showed that, compared with the traditional non-Gemini, quaternary ammonium salt type surfactants, Gemini surfactants Cm-3(0H)-DM (m=12,14,16,18) have a higher surface activity and two orders of magnitude lower critical micelle concentration (CMC). Emulsifying properties and foaming performance is superior to the traditional surfactant. Under low concentration, the UV absorbance of Gemini surfactants was in conformity with the lambert-beer’s law rule.At last, static weight loss method and electrochemical standard were introduced to study the Gemini surfactants on the corrosion performance of Q235 steel plate and its adsorption mechanism on the metal surface, in the meantime, the relations among dosage of Gemini surfactant, corrosion temperature, concentration of hydrochloric acid and corrosion time on the corrosion of Q235 steel plate were studied. The results showed that, in the static weight-loss method, Gemini surfactant Cm-3(OH)-DM had good corrosion inhibition on metal surface. When the concentration of Gemini surfactant reaches the CMC value, the corrosion rate can reach to more than 95%. The influence of corrosion temperature is larger, the corrosion rate under 25 ℃ is five times quicket than that of 55℃. In spite of the change of hydrochloric acid content on the corrosion rate,the corrosion inhibition rate is not large. As the extension of corrosion time during 4 to 6 h, changes basically no longer happened, and corrosion reaction come to an end. The study on the Tafel polarization curve showed that, polarization curve moved to the low current density and the corrosion potential Ecorr moved to forward direction in the systems with Gemini surfactant added, mainly for the anode electrode inhibition of mixed corrosion inhibitor. In the EIS impedance spectroscopy study, when adding different concentration of Gemini surfactants, the radiuses of a series of capacitive reactance arc have greatly increased compared with non corrosion inhibitors. The adsorption of four kinds of corrosion inhibitor molecules on the metal surface follows the Langmuir adsorption theorem and the free energy of the adsorption process is bellow zero (ΔG< O). All of the adsorption processes of these four kinds of corrosion inhibitors act spontaneously.